The present invention relates generally to construction castings, and more particularly to manhole, grate, catch basin, trench drain and hatch assemblies for covering openings and access points (hereinafter “covers”).
Typically, manholes and other types of hatches must be covered either fully or partially (as with a grate) because they are needed in places where they are crossed over by pedestrians, cars, trucks, and even aircraft. Some of these manholes and hatches have hinged covers that can be conveniently opened and closed. Unlike non-hinged covers, hinged covers cannot become partially unseated as can happen with a sewer surcharge. Hinged covers may also be opened more easily than non-hinged covers.
One type of hinged cover is shown in Defrance et al., U.S. Pat. No. 4,840,514. Defrance discloses a manhole assembly having a lid that is hinged to a frame with a T-shaped lug. There are two principal disadvantages to this particular construction. First, in order to remove or replace the cover itself, something that is periodically necessary, an operator has to be able to lift the cover straight up to release it from the position in which it is held open. Given the weight and size of most such covers, this is a particularly difficult task. Second, these hinged covers cannot be lifted with ordinary levers thus requiring the application of brute force.
Another type of hinged cover is shown in a European Patent Office publication for Saint-Gobain PAM, EP 1160382. This hinged cover locks by dropping a lug down into a hinge receptor, requiring one to lift the cover before it can be lowered. This causes the user to lift the weight of the cover each time it is used, even when the cover is not removed from the frame.
Like manhole and hatch assemblies, trench drain grates and solid covers are used in places where they are crossed over by pedestrians, cars, trucks, and even aircraft, and are not easily accessed. Trench drain and grate covers fit into a frame that typically spans the width of a driveway or other area where drainage or ventilation is desirable. Frequently, it is necessary to fasten these grates and covers to the frames. In usual applications, each separate cover is bolted to the frame with a number of bolts—typically one in each corner or otherwise fastened with one of many types of an internal mechanical locking device. If one desires access to the trench or drain below the cover, each bolt must be removed or the mechanical locking device released so the cover can be lifted and removed. Lid removal is time consuming and sometimes difficult due to damaged bolts, broken mechanical locking devices or dirt. In addition, bolt patterns and mechanical lifting devices may change due to wear, and it may be difficult to replace the removed lids if they do not have the same orientation as they did prior to removal.
Accordingly, there is a well established need for a connector used in conjunction with various construction castings that is simple and easy to use and maintain. Because construction castings are typically heavy, there is a further need for construction castings that are more ergonomic for lid or cover opening and removal.